This invention relates to mobile vehicles that have closed circuit television systems comprising one or more video cameras for observing fields of view that may be inconvenient, or even impossible, for an occupant of a vehicle to see, either via direct line-of-sight or indirectly via a mirror, and one or more video monitors for displaying fields of view observed by such cameras.
Certain mobile vehicles, such as trucks or motor homes for example, may have closed circuit television systems for enabling an occupant of the vehicle to observe fields of view in and/or around the vehicle. One example of such a closed circuit television system comprises a video television monitor having a screen disposed for viewing by an occupant of the vehicle, the driver of the vehicle for example. One or more video television cameras are situated to observe one or more fields of view that may be inconvenient, or even impossible, for the driver to see, either by direct line-of-sight viewing or indirect viewing via a mirror or mirrors. One video camera may observe a field of view to the rear of the vehicle; another camera may observe a field of view to a blind side of the vehicle, such as to the right rear in a vehicle where the driver sits on the left side toward the front of the vehicle. By suitable switching arrangements, the video cameras may be selectively switched to the single monitor. Alternatively, the vehicle may have a devoted monitor for each camera.
Regardless of the particular number of cameras and the particular number of monitors in a mobile vehicle, it is customary to connect a remote television camera to a television monitor by running coaxial cable within the vehicle. The cable carries video signals representing the field of view observed by the camera to the monitor.
It is believed that certain mobile closed circuit television systems can perform satisfactorily at slower frame rates than those commonly used in commercial broadcast television. Slower frame rates can reduce the frequency of data transmission, and hence reduce system bandwidth. Sufficient bandwidth reduction may enable video data to be transmitted satisfactorily by other than coaxial cable.
It is further believed that the connection of remote video cameras to video monitors by media other than coaxial cables could be useful in equipping certain vehicles with closed circuit television systems. For example, the availability of such a system may facilitate a Truck Equipment Manufacturer""s installation of a system because coaxial cables do not have to fabricated to desired lengths and then routed within a vehicle.
The present invention relates to a mobile closed circuit television system in which a pre-existing data communication system in a vehicle is used as a medium for transmitting video data from an on-board television camera to an on-board television monitor. Such a pre-existing data communication system comprises a data bus that serves various electric and electronic devices throughout a vehicle. The data bus is embodied in wiring modules, or wiring harnesses, that run throughout the vehicle. Such wiring connects remote devices with electronic processors and allows electronic processors to communicate with each other. For example, data obtained from various sensors can be communicated to processors that process the data for control and/or informational purposes. The processors may issue appropriate commands to manage various systems of the vehicle, and/or may display information to the driver.
Such a pre-existing data bus may utilize an operating protocol that is embodied in a published standard that is recognized by the industry. SAE Standard J1939, published by the Society of Automotive Engineers, is an example of a standard that is being increasingly used in the manufacture of certain motor vehicles to define how data is to be communicated over a vehicle data bus,
In accordance with certain principles of the invention, data from a frame captured by a television camera is processed by an electronic module that utilizes the operating protocol embodied in SAE Standard J1939. That processing converts the video data to a form that allows it to be transmitted over a data bus adhering to the SAE Standard. The data is then converted back to a form that can be used by a monitor to display the captured frame on the monitor screen. The rate at which captured frames are presented on the monitor screen is slower than that typically used in commercial broadcast television, but this slower rate may be quite suitable for various applications of closed circuit television to a mobile vehicle. And it makes use of pre-existing wiring in a vehicle for data transmission, rather than requiring installation of coaxial cable.
Accordingly a general aspect of the within claimed invention relates to a mobile vehicle comprising: a closed circuit television system; an electronic data link through which various devices in the vehicle communicate according to a defined data transmission protocol for the vehicle; the closed circuit television system comprising a television camera for observing a field of view and providing signals representing the field of view; a monitor for presenting an image of the field of view; and a processing system for processing the signals from the television camera into signals for the monitor, the processing system comprising a processor that processes the signals from the television camera to create signals defining video frames corresponding to fields of view observed by the video camera at various times and conforming to the defined data transmission protocol for the vehicle and that places the created signals on the electronic data link for transmission to the monitor.
Another general aspect of the within claimed invention relates to a method of equipping a mobile vehicle with a closed circuit television system, the method comprising: providing a vehicle that has a pre-existing electronic data link through which various devices in the vehicle communicate according to a defined data transmission protocol for the vehicle; installing in the vehicle a closed circuit television system comprising a television camera for observing a field of view and a television monitor for presenting an image of the field of view; processing signals from the camera that represent an image frame of the field of view observed by the camera to create signals conforming to the defined data transmission protocol for the vehicle; and placing the created signals on the electronic data link for transmission to the monitor.
The foregoing, along with further features and advantages, and other aspects, of the invention, will be seen in the following disclosure of a presently preferred embodiment of the invention depicting the best mode contemplated at this time for carrying out the invention. The disclosure includes drawings, briefly described as follows.